The present invention relates to an apparatus for utilizing waste gas from electric furnaces, and more particularly to a novel apparatus for use with scrap preheaters which utilize the sensible heat of waste gas from electric furnaces, for preventing secondary pollution that will result from noxious odor and white fumes, i.e. hydrocarbon gases, released from the preheater.
Waste gas apparatus for electric furnaces usually comprises a combustion chamber or heat storage chamber for receiving hot waste gas from the electric furnace through a water-cooled duct, a preheater bucket for receiving part or all of the hot waste gas from the chamber by way of a preheater duct and a hood to preheat the scrap accommodated therein, and a dust collector connected to the bucket for releasing the preheating waste gas to the atmosphere after the gas has been subjected to heat exchange with the scrap within the bucket.
The scrap charged in the preheating bucket is heated by direct contact with the waste gas, and the oils, rubbers, plastics and other extraneous materials contained in the scrap are incompletely burned or baked, inevitably releasing white smoke or fumes and noxious odors into the resulting waste gas. Accordingly the waste gas, if released to the atmsophere, will cause secondary pollution. An afterburning chamber is therefore usually provided between the preheater bucket and the dust collector for burning the oils, organic materials, etc. contained in the preheating waste gas.
However, even if a waste gas supply is introduced into the afterburning chamber from the heat storage chamber via a main duct, the waste gas resulting from preheating can not be burnt completely with the heat of the gas supply only, so that an auxiliary burner or the like is needed for the afterburning chamber. Consequently it is impossible to achieve savings in energy, while the apparatus involves problems, for example, in maintenance.